Cold-induced bronchospasm in normal and sensitized rabbits.

Area of Science:

• Respiratory Physiology
• Allergy and Immunology

Background:

• Cold air inhalation can induce bronchospasm.
• Airway hyperresponsiveness is a key feature in allergic conditions.

Purpose of the Study:

• To investigate the mechanisms of cold-induced bronchospasm in rabbits.
• To evaluate the role of the vagus nerve and local factors in this response.
• To assess the effect of sodium cromoglycate (SCG) on cold-induced bronchospasm.

Main Methods:

• Studied lung resistance changes in anesthetized rabbits exposed to cold air.
• Compared normal and bovine serum albumin-sensitized rabbits.
• Administered SCG and performed vagotomy to assess their effects.
• Measured airway responsiveness to histamine.

Main Results:

• Cold-induced bronchospasm was greater in sensitized rabbits.
• Vagotomy abolished the cold air response, while SCG significantly reduced it.
• SCG and vagotomy had similar effects in normal and sensitized rabbits.
• Sensitized rabbits exhibited hyperresponsiveness to both cold air and histamine.

Conclusions:

• Cold-induced bronchospasm is primarily mediated by a vagal reflex.
• Local humoral factors enhance and prolong the vagal reflex effects.
• Increased cold air response in sensitized rabbits is likely due to non-specific bronchial hyperresponsiveness, not increased inflammatory mediators.